Because that, when they knew God, they glorified [him] not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Berean Study Bible (BSB) - Romans 1:21 >For although they knew God, they neither glorified Him as God nor gave thanks to Him, but they became futile in their thinking and darkened in their foolish hearts.
Textus Receptus (TR) - Romans 1:21 >διότι γνόντες τὸν Θεόν, οὐχ ὡς Θεὸν ἐδόξασαν ἢ εὐχαρίστησαν, ἀλλ᾿ ἐματαιώθησαν ἐν τοῖς διαλογισμοῖς αὐτῶν, καὶ ἐσκοτίσθη ἡ ἀσύνετος αὐτῶν καρδία.